Structure and method of connecting I-type prestressed concrete beams using steel brackets

ABSTRACT

A structure and method of connecting a plurality of PSC-I beams (PSC-I beams) to each other using steel brackets. The beam connecting structure, each having a sheath pipe therein, includes an end plate which is mounted on each of both ends of each of the PSC-I beams, with a through hole provided on an upper portion of the end plate to correspond to the sheath pipe embedded in each of the PSC-I beams; a steel bracket integrally which is provided on the end plate to be perpendicular to the end plate; a bracket coupling plate to integrally couple the aligned steel brackets to each other; a bottom connecting plate which is provided on lower ends of the aligned steel brackets to connect the steel brackets to each other; a connecting sheath pipe which is provided between the PSC-I beams so that both ends of the connecting sheath pipe are respectively inserted into the through holes of the neighboring end plates of the PSC-I beams while the PSC-I beams are arranged linearly; a prestress strand which is inserted in the sheath pipes of the PSC-I beams and the connecting sheath pipe; and a concrete part which is filled in a space between the PSC-I beams to embed the aligned steel brackets, the bracket coupling plate and the connecting sheath pipe in the concrete part.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a structure and a method ofconnecting I-type prestressed concrete beams (hereinafter referred tosimply as PSC-I beams) using steel brackets, and more particularly, to astructure and a method of connecting a plurality of PSC-I beams,separately precasted on the ground, to each other using steel brackets.

2. Description of the Related Art

FIG. 1A is a side view of a two-span bridge with a conventionalstructure for connecting two I-type prestressed concrete beams 1 (PSC-Ibeams) to each other. The two PSC-I beams 1, used in the conventionaltwo-span bridge of FIG. 1A, are separately precasted on the ground.Thereafter, each of the PSC-I beams 1 is independently placed between apier 2 and a pair of support grounds, which support both ends of thetwo-span bridge, to form a simple beam system. At this time, the twoPSC-I beams 1 are connected to each other by only a concrete slab 16which is constructed on the two PSC-I beams 1. Otherwise, the pluralityof PSC-I beams 1 may be connected to each other by another conventionalbeam connecting structure, as shown in FIG. 1B.

To construct a bridge with the conventional beam connecting structure ofFIG. 1B, each of PSC-I beams 1 is precasted, so that a plurality ofreinforcing bars 17 are embedded in each of the PSC-I beams 1 while anend of each of the reinforcing bars 17 is exposed from an end of thePSC-I beam 1 to a predetermined distance. Thereafter, each of the PSC-Ibeams 1 are placed between the pair of support grounds and the piers 2.There is a predetermined space between ends of the two PSC-I beams 1placed on the piers 2. When the PSC-I beams 1 are linearly arranged, thereinforcing bars 17 exposed from an end of one of the PSC-I beams 1 arerespectively coupled to the reinforcing bars 17 exposed from an end of aneighboring PSC-I beam 1. Thereafter, concrete is filled in each of thepredetermined space defined between the ends of the PSC-I beams 1 toform a concrete part 15. The concrete slab 16 is, thereafter, integrallyconstructed on the PSC-I beams 1 and the concrete parts 15.

However, in the conventional structure for connecting the PSC-I beams,each of the PSC-I beams 1 has a role as the simple beam system. That is,an additional support bearing 3 is provided under each of both ends ofthe PSC-I beam 1 to support the PSC-I beams 1 on the pier 2 and thesupport grounds. Therefore, at least two support bearings 3 must beplaced on the pier 2. At this time, ideally, a reaction force against alive load must be evenly applied to the two support bearings 3 on thepier 2. However, in reality, one of the two support bearings 3 has anegative (−) reaction force, and the other support bearing 3 has anexcessive positive (+) reaction force. Therefore, the support bearing 3,which has the excessive positive (+) reaction force, must have a largercapacity. Thus, the conventional beam connecting structure imposesexcessive constructing costs on users.

In the bridge with the conventional beam connecting structure of FIG.1B, the concrete part 15 is filled in the space defined between thePSC-I beams. At this time, a cold joint is undesirably generated on eachof junctions of both ends of the concrete part 15 and the ends of thePSC-I beams 1. Therefore, a crack may be generated around the cold jointby the live load. As described above, when the crack is generated aroundthe cold joint, the PSC-I beams 1 are not firmly connected to eachother. Thus, structural defect may be caused in the bridge with theconventional beam connecting structure.

In the meantime, a negative moment is generated around parts of thePSC-I beams, which are supported on the pier 2. However, theconventional beam connecting structure does not have sufficient strengthfor resistance against the above-mentioned negative moment. Therefore,tensile stress is generated around a part of the concrete slab 16 whichis positioned on the concrete part 15 filled between the PSC-I beams.Thus, a crack is undesirably caused around the part of the concrete slab16, which is positioned on the concrete part 15, by the above-mentionedtensile stress.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide a structure and a method of connecting aplurality of PSC-I beams to each other using end plates and steelbrackets which have higher structural durability, different from aconventional structure for connecting the plurality of PSC-I beams usingonly the reinforcing bars and concrete, so that the plurality of PSC-Ibeams are firmly connected to each other.

Another object of the present invention is to provide an structure andmethod of connecting the plurality of PSC-I beams, which has only onesupport bearing on each of piers to support the PSC-I beams, thussolving the disadvantages caused by using the plurality of supportbearings in the prior art.

In an aspect, the present invention provides an structure for connectinga plurality of PSC-I beams, each having a sheath pipe therein, to eachother. The beam connecting structure includes an end plate mounted oneach of both ends of each of the PSC-I beams, with a through holeprovided on an upper portion of the end plate to correspond to thesheath pipe embedded in each of the PSC-I beams; a steel bracketintegrally provided on the end plate to be perpendicular to the endplate, so that the steel brackets of the neighboring end plates of thePSC-I beams are aligned with each other while the PSC-I beams arearranged linearly; a bracket coupling plate to integrally couple thealigned steel brackets to each other; a bottom connecting plate providedon lower ends of the aligned steel brackets to connect the steelbrackets to each other; a connecting sheath pipe provided between thePSC-I beams so that both ends of the connecting sheath pipe arerespectively inserted into the through holes of the neighboring endplates of the PSC-I beams while the PSC-I beams are arranged linearly,thereby the sheath pipes of the PSC-I beams are connected to each other;a prestress strand inserted in the sheath pipes of the PSC-I beams andthe connecting sheath pipe while the PSC-I beams are linearly connectedto each other, the PC strand being prestressed in the sheath pipes andthe connecting sheath pipe for transfer of prestress to the PSC-I beams;and a concrete part filled in a space between the PSC-I beams to embedthe aligned steel brackets, the bracket coupling plate and theconnecting sheath pipe in the concrete part.

In another aspect, the present invention provides a method of connectinga plurality of PSC-I beams, each having a sheath pipe therein, to eachother. The beam connecting method includes mounting an end plate on eachof both ends of each of the PSC-I beams, with a through hole provided onan upper portion of the end plate to correspond to the sheath pipeembedded in each of the PSC-I beams; providing integrally a steelbracket on the end plate to be perpendicular to the end plate; placingthe PSC-I beams on a plurality of piers while the steel brackets of theneighboring end plates of the PSC-I beams are aligned with each other ona bottom connecting plate placed on a support bearing mounted on each ofthe plurality of piers; mounting the aligned steel brackets of theneighboring end plates of the PSC-I beams to the bottom connecting plateto connect the steel brackets to each other, mounting a bracket couplingplate to the aligned steel brackets to integrally couple the alignedsteel brackets to each other, placing a longitudinal connecting bolt onupper portions of the aligned steel brackets to connect the steelbrackets to each other; placing a connecting sheath pipe between thePSC-I beams so that both ends of the connecting sheath pipe arerespectively inserted into the through holes of the neighboring endplates of the PSC-I beams while the PSC-I beams are arranged linearly,thereby the sheath pipes are connected to each other; inserting aprestress strand (PC strand) in the sheath pipes of the PSC-I beams andthe connecting sheath pipe while the PSC-I beams are linearly connectedto each other, and prestressing the PC strand for transfer of prestressto the PSC-I beams; and filling concrete in a space defined between thePSC-I beams to form a concrete part, thus embedding the aligned steelbrackets, the bracket coupling plate and the connecting sheath pipe inthe concrete part.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1A is a side view of a two-span bridge with a conventionalstructure for connecting two PSC-I beams to each other;

FIG. 1B is a side view showing another conventional structure forconnecting a plurality of PSC-I beams to each other;

FIG. 2 is a sectional view of one of a plurality of PSC-I beamsconnected to each other by a structure for connecting the plurality ofPSC-I beams, according to an embodiment of the present invention;

FIG. 3 is a partially broken perspective view of the PSC-I beam of FIG.2, in which a part around an end of the PSC-I beam is shown;

FIG. 4A is a side view showing a step for connecting the two PSC-I beamsof FIG. 2 to each other, in which the two PSC-I beams are placed on apier while the two PSC-I beams are arranged linearly;

FIG. 4B is a sectional view taken along the line A-A of FIG. 4A;

FIG. 5 is a side view showing a step for connecting the PSC-I beams ofFIG. 2 executed after the connecting process shown in FIG. 4A, in whicha bracket connecting plate and a connecting sheath pipe are providedbetween the neighboring end plates of the PSC-I beams;

FIG. 6A is a side view showing a state of the structure for connectingthe PSC-I beams of FIG. 2 after the connecting process shown in FIG. 5is executed, in which the aligned steel brackets are connected to eachother by the bracket connecting plate;

FIG. 6B is a sectional view taken along the line B-B of FIG. 6A;

FIG. 7 is a sectional view taken along the line C-C of FIG. 6B;

FIG. 8 is an exploded perspective view of the structure for connectingthe PSC-I beams of FIG. 2;

FIG. 9 is a partially broken perspective view showing the beamconnecting structure of FIG. 8 with a concrete part filled in a spacedefined between the PSC-I beams; and

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the attached drawings.

Reference now should be made to the drawings, in which the samereference numerals are used throughout the different drawings todesignate the same or similar components.

FIG. 2 is a sectional view of one of a plurality of I-type prestressedconcrete beams 1 (PSC-I beams) connected to each other with a structurefor connecting the plurality of PSC-I beams, according to an embodimentof the present invention. FIG. 3 is a partially broken perspective viewof the PSC-I beam 1 of FIG. 2, in which a part around an end of thePSC-I beam 1 is shown. As shown in FIGS. 2 and 3, in the beam connectingstructure according to the present invention, each of the PSC-I beams,made of concrete, has a sheath pipe 18 therein. That is, when the PSC-Ibeam 1 is produced, the sheath pipe 18 is previously embedded in theconcrete. The sheath pipe 18 receives therein a prestress strand. Thebeam connecting structure of the present invention includes an end plate4 which is mounted on at least one of both ends of each of the PSC-Ibeams 1. In detailed, a plurality of anchor bolts 7 are previouslyembedded in the concrete of at least one of both ends of each of thePSC-I beams 1, while each of the PSC-I beam 1 is precasted. Thereafter,the end plate 4 is fitted over ends of the plurality of anchor bolts 7.A nut 13 is, thereafter, tightened to each of the plurality of anchorbolts 7 to couple the end plate 4 to the end of the PSC-I beam 1.

In the beam connecting structure of the present invention, two steelbrackets 6 are integrally provided on each of the end plates 4 bywelding to be perpendicular to the end plate 4. A through hole 5 isprovided on an upper portion of the end plate 4 to correspond to thesheath pipe 18 which is embedded in each of the PSC-I beams 1. Aplurality of bolt holes are provided on each of the steel brackets 6, sothat the steel bracket 6 is coupled to a following bracket couplingplate 9 by a plurality of coupling bolts 10 and coupling nuts 10 a whichwill be described later herein.

FIG. 4A is a side view showing a step for connecting the two PSC-I beams1 of FIG. 2 to each other, in which the two PSC-I beams 1 are placed ona pier 2 while the two PSC-I beams 1 are arranged linearly. FIG. 4B is asectional view taken along the line A-A of FIG. 4A.

As shown in FIGS. 4A and 4B, a support bearing 3 is provided on the pier2 before the PSC-I beams 1 are placed over the pier 2. A plurality oftemporary support units 14 are provided around the support bearing 3 onthe pier 2 to support the neighboring ends of the PSC-I beams 1 on thepier 2. A bottom connecting plate 8 is placed on the support bearing 3.Thereafter, the PSC-I beams 1, separately precasted on the ground, areplaced over the pier 2 while the neighboring ends of the PSC-I beams 1are supported on the plurality of temporary support units 14. At thistime, the steel brackets 6 of the neighboring end plates 4 of the PSC-Ibeams 1 are aligned with each other on the bottom connecting plate 8.The steel brackets 6 of the neighboring end plates 4 are mounted atlower ends thereof to the bottom connecting plate 8 by welding, so thatthe steel brackets 6 are connected to each other.

FIG. 5 is a side view showing a step for connecting the PSC-I beams 1 ofFIG. 2 executed after the connecting process shown in FIG. 4A, in whicha bracket connecting plate 9 and a connecting sheath pipe 19 areprovided between the neighboring end plates 4 of the PSC-I beams 1.

As shown in FIG. 5, the connecting sheath pipe 19 is provided betweenthe PSC-I beams 1 so that both ends of the connecting sheath pipe 19 arerespectively inserted into the through holes 5 which are respectivelyprovided on the upper portions of the neighboring end plates 4 of thePSC-I beams 1, while the PSC-I beams are arranged linearly. By placingof the connecting sheath pipe 19, the sheath pipes 18 of the PSC-I beams1 are connected to each other.

In the meantime, the two bracket coupling plates 9 are respectivelyprovided on both sides of the aligned steel brackets 6 of theneighboring end plates 4. The bracket coupling plates 9 and the alignedsteel brackets 6 are integrally coupled to each other by the pluralityof coupling bolts 10 and the plurality of nuts 10 a. Therefore, thealigned steel brackets 6 are connected to each other by the bottomconnecting plate 3, in addition to the bracket coupling plates 9.

FIG. 6A is a side view showing a state of the structure for connectingthe PSC-I beams 1 after the connecting step shown in FIG. 5 is executed,in which the aligned steel brackets 6 are connected to each other by thebracket connecting plate 9. FIG. 6B is a sectional view taken along theline B-B of FIG. 6A. As show in FIGS. 6A and 6B, the aligned steelbrackets 6 are also connected to each other by a plurality oflongitudinal connecting bolts 12. That is, a bolt holding unit 11 isprovided on an upper end of each of the steel brackets 6 of the PSC-Ibeams 1. A connecting nut 21 is tightened to each of the longitudinalconnecting bolts 12 while the longitudinal connecting bolt 12 passesthrough both the bolt holding units 11 of the aligned steel brackets 6.Thus, the steel brackets 6 are more firmly connected to each other bythe longitudinal connecting bolts 12 and the connecting nuts 21. At thistime, the bolt holding unit 11 is mounted to an upper support plate 22which is provided on the upper end of each of the steel brackets 6.

FIG. 7 is a sectional view taken along the line C-C of FIG. 6B. Asdescribed above, in a state in that the sheath pipes 18 of the PSC-Ibeams 1 are connected to each other by the connecting sheath pipe 19, aprestress strand 20 is continuously inserted in the sheath pipes 18 andthe connecting sheath pipe 19. Particularly, even when the PSC-I beams 1are placed over at least two spans, the strand 20 is continuouslyinserted in every sheath pipe 18 and connecting sheath pipe 19 throughevery span. At this time, the strand 20 may be inserted in the sheathpipe 18 and the connecting sheath pipe 19, after a space defined betweenthe PSC-I beams 1 receives concrete, which will be described laterherein. The strand 20, inserted in the every sheath pipe 18 and theconnecting sheath pipe 19, is prestressed for transfer of prestressedforce to the PSC-I beams 1, before or after a following concrete slab 16is constructed on the PSC-I beams 1.

FIG. 8 is an exploded perspective view of the structure for connectingthe above-mentioned PSC-I beams 1. After, as shown in FIG. 7, the steelbrackets 6 of the PSC-I beams 1 are connected to each other, theconcrete is filled in the space defined between the PSC-I beams 1 toform a concrete part 15. Thus, the aligned steel brackets 6, the bracketcoupling plate 9 and the connecting sheath pipe 19 are embedded in theconcrete part 15. FIG. 9 is a partially broken perspective view showingthe beam connecting structure of FIG. 8 with the above-mentionedconcrete part 15 filled in the space defined between the PSC-I beams 1.As shown in FIG. 9, the temporary support units 14, provided under theneighboring ends of the PSC-I beams 1, are removed, after the concretepart 15 is filled in the space defined between the PSC-I beams 1. Thus,only the support bearing 3 on each of the piers 2 supports the bridgewith the beam connecting structure of the present invention.

As described above, the plurality of PSC-I beams 1 are firmly connectedto each other by the beam connecting structure of the present invention.Thus, the bridge with the beam connecting structure forms a continuousbeam system. Therefore, the bridge with the beam connecting structurereduces the positive moment generated in the PSC-I beams 1, thusreducing the size of the PSC-I beams 1 in comparison to a bridge withconventional beam connecting structure.

Generally, in case of bridges with continuous beam systems, the positivemoment is reduced. However, negative moments are generated in upperportions of the bridges by dead loads caused by the weight of theconcrete slab 16 and additional asphalt pavements. In above state, whencars pass through the bridges, the negative moments are increased.

In the bridge with the beam connecting structure according to thepresent invention, the above-mentioned negative moment is also generatedin the bridge. However, the beam connecting structure of the presentinvention has the plurality of longitudinal connecting bolts 12 towithstand tensile stress generated by the negative moment. Furthermore,as described above with reference to FIG. 7, the PC strand 20 iscontinuously arranged in the bridge. Therefore, the PC strand 20 alsowithstands the tensile stress.

As described above, the present invention provides a structure and amethod of connecting a plurality of PSC-I beams to each other usingsteel brackets, bracket connecting plates, longitudinal connectingbolts, a connecting bottom plate and a concrete part, different fromconventional structure for connecting the PSC-I beams using a pluralityof reinforcing bars and a concrete part. That is, the beam connectingstructure of the present invention more firmly connects the plurality ofPSC-I beams to each other in comparison with the conventional beamconnecting structure which cannot sufficiently connect the PSC-I beamsto each other to form a simple beam system.

Furthermore, the beam connecting structure of the present invention hasa prestress strand which is arranged through entire spans. Therefore,the prestress force is evenly transferred to a concrete part filled in aspace defined between the PSC-I beams, in addition to the PSC-I beams.Thus, the bridge with the beam connecting structure efficiently respondsto a tensile stress generated by a negative moment.

In addition, the bridge with the beam connecting structure according tothe present invention has sufficient strength to respond the negativemoment generated in the space defined between the PSC-I beams.Therefore, the bridge with the beam connecting structure of the presentinvention completely forms a continuous beam system. Thus, both a sizeof each of the PSC-I beams and construction costs are reduced incomparison with the conventional beam connecting structure with thesimple beam system.

Furthermore, even though the beam connecting structure of the presentinvention has only one support bearing on each of piers, different fromthe conventional beam connecting structure with at least two supportbearings on each of the piers, the bridge is sufficiently supported onthe piers.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1. A structure for connecting a plurality of I-type prestressed concretebeams (PSC-I beams), each having a sheath pipe therein, to each other,the structure comprising: an end plate mounted on each of both ends ofeach of the PSC-I beams, with a through hole provided on an upperportion of the end plate to correspond to the sheath pipe embedded ineach of the PSC-I beams; steel brackets integrally provided on the endplate to be perpendicular to the end plate, so that the steel bracketsof the neighboring end plates of the PSC-I beams are aligned with eachother while the PSC-I beams are arranged linearly; bracket couplingplates to integrally couple the aligned steel brackets to each other; abottom connecting plate provided on lower ends of the aligned steelbrackets to connect the steel brackets to each other; a connectingsheath pipe provided between the PSC-I beams so that both ends of theconnecting sheath pipe are respectively inserted into the through holesof the neighboring end plates of the PSC-I beams while the PSC-I beamsare arranged linearly, thereby the sheath pipes of the PSC-I beams areconnected to each other; a prestress strand inserted in the sheath pipesof the PSC-I beams and the connecting sheath pipe while the PSC-I beamsare linearly connected to each other, the strand being prestressed inthe sheath pipes and the connecting sheath pipe for transfer ofprestress force to the PSC-I beams; and a concrete part filled in aspace between the PSC-I beams to embed the aligned steel brackets, thebracket coupling plate and the connecting sheath pipe in the concretepart.
 2. The structure according to claim 1, further comprising:longitudinal connecting bolts provided on upper portions of the alignedsteel brackets to connect the steel brackets to each other
 3. Thestructure according to claim 1, further comprising: a support bearingprovided on each of a plurality of piers, wherein the bottom connectingplate is placed on the support bearing, and the lower ends of thealigned steel brackets are mounted to the bottom connecting plate, sothat the steel brackets are connected to each other.
 4. A method ofconnecting a plurality of I-type prestressed concrete beams (PSC-Ibeams), each having a sheath pipe therein, to each other, the methodcomprising: mounting an end plate on each of both ends of each of thePSC-I beams, with a through hole provided on an upper portion of the endplate to correspond to the sheath pipe embedded in each of the PSC-Ibeams; providing integrally steel brackets on the end plate to beperpendicular to the end plate; placing the PSC-I beams on a pluralityof piers while the steel brackets of the neighboring end plates of thePSC-I beams are aligned with each other on a bottom connecting plateplaced on a support bearing mounted on each of the plurality of piers;mounting the aligned steel brackets of the neighboring end plates of thePSC-I beams to the bottom connecting plate to connect the steel bracketsto each other, mounting a bracket coupling plate to the aligned steelbrackets to integrally couple the aligned steel brackets to each other,placing a longitudinal connecting bolt on upper portions of the alignedsteel brackets to connect the steel brackets to each other, placing aconnecting sheath pipe between the PSC-I beams so that both ends of theconnecting sheath pipe are respectively inserted into the through holesof the neighboring end plates of the PSC-I beams while the PSC-I beamsare arranged linearly, thereby the sheath pipes are connected to eachother, inserting a prestress strand in the sheath pipes of the PSC-Ibeams and the connecting sheath pipe while the PSC-I beams are linearlyconnected to each other, and prestressing the strand for transfer ofprestress to the PSC-I beams; and filling concrete in a space definedbetween the PSC-I beams to form a concrete part, thus embedding thealigned steel brackets, the bracket coupling plate and the connectingsheath pipe in the concrete part.